Scientists have come up with their best reason yet for getting kids off the computer and into fitness.
New research from the Liggins Institute at the University of Auckland shows if a person has an active childhood, they'll be healthier later in life - even if they stop exercising before puberty.
The researchers analysed rats on a high-fat diet and allowed some of them to exercise on a wheel.
The rats stopped exercising before puberty.
"What we saw is that the rats that had exercised early on in life, they changed the way their bones responded, they changed the way they grew,"says Justin O'Sullivan a molecular geneticist at the Liggins Institute.
"It meant that their metabolism, the way their bodies were working was different and that early life exercise had basically programmed them even after puberty. So they basically set themselves up for later in life."
Mr O'Sullivan says the health benefits continued long after the rats stopped exercising.
"For children we think that this means that if you exercise early on in life we know it's very beneficial and we think that if you exercise before puberty that some of those changes will be retained long after puberty, much later into life," Mr O'Sullivan says.
The researchers say the exercise doesn't need to be high-intensity and that simple play is all that's required.
They also don't recommend children ever stop exercising and say staying active throughout your entire life is the best approach.
The research was funded by Arthritis New Zealand and the Health Research Council of New Zealand.